Blind fastener

ABSTRACT

A blind fastener and method for making such fastener that has a flanged outer sleeve and a flanged inner sleeve that are secured together, wherein the outer sleeve has a socket that receives a lug from the inner sleeve to provide joint axial movement and wherein the outer sleeve has a plurality of slits that receives at least one radial projection from the inner sleeve to prevent rotation between sleeves. The inner sleeve has a thinner upper portion and a thicker lower portion with a score line therebetween to facilitate the separation of this portion. The inner sleeve has a central threaded bore to receive a threaded bolt for fastening purposes and to upset the outer sleeve relative to the flanged portion thereof to secure such fastener to a thin workpiece.

BACKGROUND OF THE INVENTION

This invention relates to blind fasteners of the type that can beinstalled entirely from one side of a structure and more particularly toa new and improved blind fastener that is inexpensive to manufacturesuch as one that can be made entirely from plastic materials.

The blind fasteners heretofore used consisted of various designs whereinthe fastener had a tubular or cylindrical body with a head on an upperportion that was slotted and a lower body portion that was threaded. Inthe process of securing such fasteners to the plate structure, the upperslotted body portion would be deformed or folded outwardly therebypresenting a flanged and deformed portion which would secure thefastener to the plate structure with the head on one side and thedeformed flanged portion on the other side.

Another requirement of such blind fasteners is that they be easy tomanufacture and operate in a facile manner. The fastener of the presentinvention is particularly easy to manufacture because it can be madefrom a plastic material as in an extrusion or molding process. Further,the application of the blind fastener to a workpiece is accomplished ina facile manner yet insuring a firm attachment to such workpiece.

SUMMARY OF THE INVENTION

A blind fastener and the method of making such fastener for attachmentto a thin plate or workpiece wherein an outer sleeve has a flanged headfor seating on the workpiece and has it cylindrical body portionextending through a bore in the workpiece for deformation such that itsbulging will captively secure the fastener to the workpiece. The outersleeve has longitudinally extending slits and sockets. An inner sleeveis located within the outer sleeve and is attached thereto by a radiallug extending into the socket and projections extending into the slitsof the outer sleeve. The inner sleeve has a central bore to receive abolt for upsetting and for attaching another object to the fastener andthe workpiece.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a blind fastener showing thedraw bolt removed;

FIG. 2 is a cross sectional view of the blind fastener showing, thebolt, inner sleeve and outer sleeve;

FIG. 3 is an end view taken on line 3--3 of FIG. 2 showing the cap endof the outer sleeve;

FIG. 4 is a cross-sectional view taken on line 4--4 of FIG. 2 showingthe end locking projections on the inner sleeve integral or locking theouter sleeve and with the larger projection extending to surface of theouter sleeve;

FIG. 5 is a cross sectional view taken on line 5--5 of FIG. 2 showingthe projections on the inner sleeve recesses in the outer sleeve;

FIG. 6 sectional view taken on line 5--5 of FIG. 2 showing theprojections of the inner sleeve extending into slots or slits on theouter sleeve with the serrations on the inner and outer sleeve inlocking engagement with the ribs between the slots of the outer sleeve;

FIG. 7 is a view similar to FIG. 2 showing the fastener installedthrough a blind borehole, with the ribs of the outer sleeve expanded toengage the blind wall surface of the workpiece and the serrations of theinner and outer sleeves in a locking relationship, preventing thefastener from returning to it's extended position shown in FIG. 2;

FIG. 8 is an end view taken on line 8--8 of FIG. 7 showing the ribsexpanded on the outer sleeve and engaging the blind wall surface of theworkpiece;

FIG. 9 is a cross sectional view of the blind fastener being installedon a workpiece with the bolt and inner sleeve pulled from fastener andwith the outer sleeve captively secured to the workpiece;

FIGS. 10 and 11 are views similar to FIG. 9 showing the sequence ofcompleting the assembling of the fastener to the workpiece;

FIG. 12 is a detached perspective view of the inner sleeve, showing theflange, serrations, with projection locking lugs;

FIG. 13 is an end view of the inner sleeve taken on line 13--13 of FIG.12, showing the locking lugs;

FIG. 14 is a sectional view of the inner sleeve taken on line 14--14 ofFIG. 12, showing the projections and the enlarged end serrations betweenthe projections;

FIG. 15 is a detached perspective view of the outer sleeve, showing themounting flange, the serrated bore, slots, expanding ribs, and socketthat retains the locking lug of the inner sleeve and the capped end;

FIG. 16 is a cross sectional view of the outer sleeve taken on line16--16 of FIG. 15, showing the socket that retain the locking lugs onthe inner sleeve;

FIG. 17 is a sectional view of the outer sleeve taken on line 17--17 ofFIG. 15, showing the fastener locking ribs, slots and serrations;

FIG. 18A is a side elevational view of the bolt for use with thefastener;

FIG. 18B is a cross sectional view of the mold receiving the bolt formolding the inner sleeve thereto;

FIG. 18C is a cross sectional view of the mold, the cast inner sleeve inintegral relationship with the bolt;

FIG. 18D is a side elevational view of the cast inner sleeve and bolt ina mold for casting the outer sleeve; and

FIG. 18E is a cross sectional view of the mold and cast outer sleeve inintegral relationship with the inner sleeve and bolt prior to removal ofthe mold to form the blind fastener.

DETAILED DESCRIPTION

Referring to the drawings wherein like reference numerals designate likeor corresponding parts throughout the several views, there is shown inFIG. 1 a bolt 20 with an upper flanged head 21 and a depending,longitudinally extending threaded cylindrical portion 22. Flanged head21 has a slot 23 for selectively rotating such bolt 20.

Bolt 20 is threadedly received by an inner sleeve 25 having a centrallongitudinally extending threaded bore 26, an outer serrated surface 27,and a flange 28. The lower end portion of inner sleeve 25 has aplurality of circumferentially spaced depending projections, lugs orlocking lugs 29-30-31. Lug 29 is a locking projection and issubstantially rectangular in cross section in plan view as depicted byFIGS. 4 and 12 with lugs 30 and 31 having a sharp projecting edge orsharp locking projection profile for a purpose to be described. Theimmediate surface above the lower end portion of inner sleeve 25 has asmooth outer cylindrical surface 35. Above cylindrical surface 35 are aplurality of projections 36-37-38. Projection 36 is rectangular in crosssection in plan view while projections 37 and 38 are triangular in crosssection in plan view. The cross sectional wall thickness of inner sleeve25 is consistent in thickness from flange 28 to the juncture with theprojections 36-37-38 and thence the cross-sectional wall thickness ofinner sleeve 25 increases in thickness. The juncture of these twothicknesses, as clearly seen in FIGS. 9 and 10, has a scoring, incisionor indentation cut designated 40 thereat to facilitate the separation ofthe upper inner sleeve portion from the lower inner sleeve portion whichportions are designated 25a and 25b only in FIG. 11 to emphasize thatthe inner sleeve 25 will fractionalize or break up into two sectionsupon application of a force as to be described.

Surrounding and encompassing a major portion of the inner sleeve 25 isan outer sleeve or cylindrical body 42. Outer sleeve 42 has a centralbore 43 that is serrated to frictional receive the serrated outersurface of inner sleeve 25 as depicted by FIG. 2. Central bore 43extends to the very end portion 44 of outer sleeve 42, which end portion44 is closed as clearly shown by FIGS. 2 and 9. Outer sleeve 42 has aflanged head 45 at one end, opposite such other closed end portion 44.Outer sleeve 42 has a plurality of circumferentially spacedlongitudinally extending slots 47 that extend from closely adjacent theflanged head 45 to the lower portion of such sleeve 42, which slots 47register with the projections 36, 37 and 38, which prevent relativerotation between the inner sleeve 25 and the outer sleeve 42. Such slots47 of the outer sleeve 42 cooperate with the projections 36, 37 and 38of inner sleeve 25 to define rotary locking means that interconnectssuch sleeves. The material between the slots 47 form ribs designated 48in FIG. 17. Outer sleeve 42 also has a plurality of circumferentiallyspaced recesses or sockets 50-51-52 (FIG. 16). A socket is defined as anopening, recess or hollow that forms a holder for something. In theinstant structure such sockets 50-51-52 receive respectively the lowerprojections, lugs or locking lugs 29-30-31 to lock the inner sleeve 25to the outer sleeve 42. Socket 50 extends completely through the wallthickness of the outer sleeve 42 and receives the full length of thelower projection or lug 29 (FIG. 2) forming a locking lug 29 incooperation with the locking window or locking socket 50 to define axiallocking means that prevent relative axial movement between the outersleeve 42 and the inner sleeve 25. The entire blind fastener includingthe bolt 20, inner sleeve 25 and outer sleeve 42 is made or molded fromplastic material, although the invention as disclosed can use othermaterials. FIG. 18A discloses the bolt 20 which can be cast or made inseveral ways or purchased as a staple item of commerce. The bolt 20 isthen placed in a mold 55 which has an opening 56 into which the plasticmaterial can be introduced into the mold 55. The mold has a centralchamber 57 with a serrated inner surface 58 to mold the outer serratedsurface on the inner sleeve 25. As seen in FIG. 18C, the inner sleeve 25is formed complimentary to the contour of the central chamber 57including the forming of the score or incision 40 on the inner sleeves25 to facilitate the separation of the sleeve 25 into two separateportions designated as upper portion 25a and as lower portion 25b inFIG. 11. To further facilitate this separation process or tendency, thewall thickness of the upper portion 25a is thinner than the wallthickness of the lower portion 25b. The joined bolt 20 and the innersleeve 25 is then placed in a mold 60 whose inner chamber 61 iscomplimentary to the formation and molding of the outer sleeve 42 withits slots 47, ribs 48 and sockets 50-51-52. Mold 61 has an opening 62through which flowable plastic material is introduced into the mold andforms such outer sleeve 42. The newly formed blind fastener is removedfrom the mold 60 and is now ready for application to a workpiece forserving as a means for fastening an article to the workpiece.

FIG. 10 designates a thin flat sheet, or workpiece 62 which has a bore63 suitably located therein. The blind fastener as depicted by FIGS. 2and 3 is introduced into bore 63 such that the flanged head 45 is seatedagainst the upper or accessible surface of the workpiece or thin plateas viewed in FIG. 10. The views as depicted by FIGS. 1 through 18 are onan enlarged scale as the cast blind fastener is a relatively smalldiameter blind fastener that can be less than a half inch (or 1.27 cm.)in diameter, however, nothing precludes these fasteners from being oflarger diameter. The point being that these blind fasteners can be usedon thin sheet metal workpieces and accomplish a fastening that does notinterfere with the smooth outer surface of such workpieces. A draw rodor bolt 20 which is threadedly connected to the inner sleeve 25 is thenmoved upwardly relative to the flanged head 45 of outer sleeve 42 whilea suitable anvil or other means maintains a downward pressure on flangedhead 45 as illustrated by the arrow in FIG. 10 so that on continuedupward movement of bolt 20 will cause a force transfer from the innersleeve 25 to the outer sleeve 42 which will cause the ribs 48 to buckleforming a bulged portion 65 (FIGS. 10 and 11), which bulged portion 65in cooperation with the flanged head 45 captively secure the blindfastener to the structure, workpiece or thin flat sheet 62. Such upwardand downward direction as referred to above are directed to FIGS. 1through 18E and the blind fastener can also be attached to an overheadplate member in which case the directions are reversed. Continued upwardmovement of bolt 20 will cause the upper portion of inner sleeve 25 toseparate at the score line or incision 40 from the lower portion of theinner sleeve 25 as depicted by FIG. 11. The bolt 20 can then be screwedout of the upper portion of the inner sleeve 25 and can then be used toattach an item to the lower portion of the inner sleeve of the blindfastener. The variation in this process described, is that the bolt inthe initial process of upsetting the outer sleeve 42 can be threadedinto the bore 26 to a depth to fully engage the threads in the upper andlower portion of the inner sleeve 25 and that after fully upsetting theouter sleeve, bolt 20 can be rotated to where it only engages thethreads 26 of the upper portion of the inner sleeve 25. Thereaftercontinued upward movement of bolt 20 will separate the upper portion ofinner sleeve 25 from the lower portion of inner sleeve 25 as depicted byFIG. 11.

It will be apparent that, although a specific embodiment of theinvention has been described in detail, the invention is not limited tothe specifically illustrated and described construction since variationsmay be made without departing from the principles of the invention.

I claim:
 1. A blind fastener system for connecting a threaded member toa relatively thin, plate-like workpiece having a hole and an accessiblesurface comprising:an outer sleeve, said outer sleeve having an upperflange for seating on said accessible surface and a lower deformableportion for bulging into engagement with that side of said workpiecethat is opposite to said accessible surface, an inner sleeve journaledin said outer sleeve, rotary locking means interconnecting said innersleeve to said outer sleeve to prevent relative rotation of saidsleeves, axial locking means interconnecting said inner sleeve to saidouter sleeve to prevent relative axial movement therebetween, said innersleeve having a threaded central bore for connection to a threaded boltsuch that on linear movement of said bolt and said inner sleeve relativeto said flange of said outer sleeve provides a deformation and bulgingof said outer sleeve, said inner sleeve has a circumferential extendingscore line along the mid-portion thereof to define an upper portion anda lower portion wherein said score line breaks said inner sleeve toseparate said upper portion from said lower portion.
 2. A blind fasteneras set forth in claim 1 wherein said inner sleeve has a plurality ofradial projections, said rotary locking means consists of said outersleeve having a plurality of axially extending slot therethrough thatare engaged by said radial projections on said inner sleeve.
 3. A blindfastener as set forth in claim 2 wherein said axial locking meansincludes a locking lug that extends radially from said inner sleeve anda socket in said outer sleeve, and said locking lug frictionally engagessaid socket to prevent relative axial movement between said sleeves. 4.A blind fastener as set forth in claim 3 wherein the inner surface ofsaid outer sleeve is serrated, the outer surface of said inner sleeve isserrated and in frictional engagement with said serrated surface of saidouter sleeve.
 5. A blind fastener of the type having a flanged head anda cylindrical body depending therefrom, said cylindrical body capable ofpassing through a hole in a workpiece, said cylindrical body having alower portion that is deformable and is capable of being upset forengagement with the blind surface of such workpiece, said cylindricalbody having a plurality of circumferentially spaced sockets and aplurality of circumferentially spaced axially extending slots, an innersleeve mounted in said cylindrical body, said inner sleeve having aplurality of lugs engaging said sockets to provide means fortransferring axial forces from said inner sleeve to said cylindricalbody, said inner sleeve having a plurality of projections extending intosaid slots to prevent relative rotation therebetween, and said innersleeve having a central threaded bore for receiving a threaded bolt forexerting an axial force on said inner sleeve and said lugs for movingsaid lower portion of said cylindrical body upwardly toward said flangedhead for upsetting action.
 6. A blind fastener as set forth in claim 5,wherein said inner sleeve has an upper portion and a lower portion, saidlugs and said projections are located on said lower portion of saidinner sleeve, and a circumferentially extending incision is locatedbetween the juncture of said upper and lower portions of said innersleeve to separate said upper portion from said lower portion at apredetermined force therebetween as applied by such threaded bolt onsaid upper portion of said inner sleeve.
 7. A blind fastener comprisingan outer sleeve with a body portion that is attached to a thinplate-like workpiece having a hole therethrough, a top surface and abottom surface; said outer sleeve having an upper flange seating on saidupper surface; said outer sleeve having a depending portion extendingaxially from said flange that is deformed into a bulge shape forengagement with said bottom surface of said workpiece to captivelysecure said fastener to said workpiece; said outer sleeve having atleast one socket and at least one slot in its body portion; an innersleeve located within said outer sleeve and frictionally engaging saidouter sleeve; said inner sleeve having at least one radially extendinglock lug engaging said socket; said inner sleeve having at least oneradially extending projection received by said slot in said outer sleeveto prevent relative rotation therebetween; and said inner sleeve has acentral threaded bore for receiving a threaded bolt for fasteningpurposes.